Some General Bacteriology Laboratory Topics


Mixture of three biotypes of Edwardsiella tarda
on the novel, MacConkey-based "ET Agar."

Until mid-2014, I taught the Microbiology 102 laboratory course at UW-Madison (formerly "Bacteriology 102"), and we informed the students at the start that we are working with the relatively small universe of bacterial species that are "easy to grow" and, for that matter, easy to test in the laboratory. Far from being of limited consequence, they are the type of organism that can proliferate in food (causing spoilage), the general environment (participating in various levels of biodegradation), and us (causing disease), and they can also "contaminate" things in general. These organisms can be readily isolated from natural samples and food products as we will find out from time to time.

What we learn from these organisms can apply to bacteria in general – including those that cannot be cultured in a lab at all. They can also serve as models for processes that occur in higher forms of life, such as us. As time permits, we can surely go beyond the usual respiring and fermenting organisms to study phototrophs – specifically the ubiquitous purple non-sulfur photosynthetic bacteria. We are attempting to fill in "the big picture" as one sees as the course progresses. We do not wish to be memorizing a bunch of trivia that we can forget about after each quiz. And we cannot put silly "politics" before correct teaching of the subject matter.

The summaries of microbiological concepts are provided herein for those who might appreciate a somewhat organized and simplified approach to teaching these things. What too-often passes for instruction on these topics is self-contradictory with a lot of micromanipulation to cover what can be perceived as "exceptions" or "special cases" when they are not so.

  • Check out our pages on the subject of dilution theory and note that the same simple principles apply universally.
  • The same applies to pH-based differential media. As an example, the effects of aerobic deamination in differential media should not have to wait to be suddenly explained when the course gets to KIA (or TSI), as that process would have shown its effect in organic media throughout the semester.
  • Use of correct terminology is important. For example, we would never want to go out into the world and equate "strain" with "species" or vice-versa.

The following list of bacteriology laboratory topic pages form the substance of, and early versions were originally at way back in the late 1900s. This "General Microbiology" site has never been meant to serve or be represented as a U.W.-Madison "Bacteriology 102" or "Microbiology 102" site, per se – both of which are distinguished as one sees in the site outline here.

This occasionally happens and is beyond my control. To get them restored, please notify me via e-mail! Link is at the bottom of the page.

Eventually to be added to the above General Microbiology Topics list are Enrichment & Isolation Experiments and Selected Microbial Groups which are dealt with in some detail in our old, "semi-archived" Bacteriology 102 website.  As for microbial groups, the enrichment and isolation of purple non-sulfur photosynthetic bacteria should be especially interesting and workable in any introductory microbiology lab course, as phototrophy will add to the appreciation of catabolic diversity already dominated by respiration and fermentation.

  • Explanation of the General Concept of Enrichment and Isolation
  • Purple Non-Sulfur Photosynthetic Bacteria
  • Bacillus
  • Salmonella (nomenclature only; no isolation in our lab)
  • Coliforms
  • Bioluminescent Bacteria (demonstration only; no isolation in our lab)
  • Iron Bacteria (demonstration only; no isolation in our lab)

Following are links to some external websites of practical interest:

  • Prevention, Identification and Treatment of Lyme Disease. Here is an excellent and thorough resource on the subject. (I've had it, and so can you!)
  • A review and discussion of the physiology and microbiology associated with hand-washing can be found here.
  • The Types of Bacteria site is filled with updated information about helpful and harmful microbes.
  • The Differences Between Bacteria and Viruses are explained on this page which also includes a list of links to useful information that one should know about these two life forms.
  • "CELLS alive!"
  • – The Microbiology Info Portal.
  • The Tree of Life Web Project.

Draining the web of its cesspool of piracy and plagiarism is long overdue. There exist certain publicly-funded .edu sites which copy old editions (circa 2000) of many of the above-listed pages without authorization. Improvements and corrections are not reflected – nor are changes in our teaching methods and course content. Links are broken and images are missing, and an unauthorized copy of my home page is almost two decades out of date. Unfortunately these pages rank high with search engines, but happily the sites by these identity thief-wannabes are easily detected as just described.

Last modified May 12, 2020 at 6:15 PM, CDT.
John Lindquist:  homepage, complete site outline
E-mail: jlindquist001 @
(Do not include the inserted spaces.)
Department of Bacteriology, U.W.-Madison